Cable television has typically been provided to customers through coaxial cable, and much of it is strung overhead between utility poles. Inasmuch as the coaxial cable is not self-supporting, it must be supported by a support cable, and the two are typically lashed together by a spiral of wire. In many instances, there may be two or more coaxial cables supported in this manner by a single support cable.
For many years, and up until about 20 years ago, the coaxial cable employed was of a type having stranded inner and outer conductors, the outer conductor being in the form of a braid of wire. A flexible, plastic annular tube separated the conductors and provided the necessary insulation. There was also a plastic cover which surrounded the braided outer conductor and served to keep out moisture. This cable, which is still manufactured, is relatively cheap and was used extensively by the cable TV industry. However, it was found that it was not very durable, and after a period of weeks to a few years, the outer insulating cover would often crack, moisture would enter the conductors, and the insulating separator would deteriorate. This, in turn, resulted in a poor electrical performance of the cable and greatly impaired the quality of the signals transmitted on the cable.
As a result of the difficulties being experienced with coaxial cable, an improved type was developed, one wherein the outer conductor is formed of a solid aluminum tube. While this type structure provides an excellent protection insofar as moisture getting into and between the conductors is concerned, it is fairly rigid and therefore difficult to string overhead without bending it to a degree which causes it to break or deform, either of which requires a cable to be cut, the damaged portion removed, and the cables spliced back together.
As indicated above, communications cables in general are strung by lashing them to a support cable, typically between utility poles. Lashing is effected by means of a lashing machine which rides as a trolley on the support cable. Lashing machines used today are of the type which were basically developed for stringing telephone cables, and insofar as is known, none have been developed particularly for the new type, an aluminum covered coaxial cable. With a conventional lashing machine, a cable to be lashed is initially fed up from the ground through an open cavity in the underside of the lashing machine. The cavity is then closed as the lasher is pulled along the support cable. A coaxial cable is fed upward and through the end of the lasher, and a strand of lashing wire lashes the coaxial cable through the support cable at the trailing end of the lasher.
There are problems that must be dealt with. First, an extraordinary effort must be made to prevent sharp angle bends where the coaxial cable enters the lasher. Second, the cavity through which the cable is strung is typically much larger than the cross section of the cable being strung, and coaxial cable may come in contact with internal walls of the lasher and the trolley cable at various angles of engagement, which may deform or even cut the coaxial cable.
Thus, there remains a substantial problem in the installation of the new type coaxial cable, and it is the object of this invention to provide a solution to the above mentioned problems.